<solved>to set Qt.QtCreator etc. directories to PATH?

I was told in this forum to never ever put qt and qtcreator in my PATH as they can cause crashes, incompatibility issues. Of course I have come across just that in a re installation guide from an unrelated website:

"Open path editor and set the following two folder into system variable. C:\Qt\qt-5.3.1-x64-mingw482r4-sjlj\mingw64\bin” C:\CMake\bin".

I can't think of any valid reason to pollute PATH with compiler toolchain or CMake. You should only ever do that per session e.g. in a batch file, a script or a terminal session. Never permanently and system-wide. Problems caused by this can be subtle and extremely tricky to track down. It should definitely not be taught in tutorials or guides so if you want to contact the author about it I'd say go ahead.

I have come across just that in a re installation guide from an unrelated website:

"Open path editor and set the following two folder into system variable. C:\Qt\qt-5.3.1-x64-mingw482r4-sjlj\mingw64\bin” C:\CMake\bin".

If you want a detailed explanation:

The author has failed to consider the situation where multiple versions of Qt live on the same machine. If you add add them all to your PATH, your programs could pick the wrong version of a DLL and crash.

Qt Creator has the responsibility of managing the libraries; there is no need to have the Qt libs in the PATH.

The single challenging part is deployment. Users find that, without Qt in the PATH, they can't launch their app by double-clicking the executable. Adding Qt DLLs to the PATH is a quick hack to make it work, but it is too risky -- it works for some people but causes weird crashes for others. The safe and correct way to deal with this is by deploying your application properly (e.g. https://wiki.qt.io/Deploy_an_Application_on_Windows )